A printed circuit board, which is mounted in various electronic devices, includes a signal wiring layer on which a signal wiring is formed, a power feeding layer on which a power supply wiring is formed, and a via, which electrically interconnects a terminal (a power feeding terminal or a signal terminal) formed on the surface of the printed circuit board and the signal wiring layer or the power feeding layer.
On the printed circuit board, an electronic component such as, for example, a package (hereinafter, abbreviated as a PKG in some cases) including, for example, a large scale integrated (LSI) circuit may be mounted. A power supply voltage for the electronic component is applied to the power supply wiring (power feeding layer) of the printed circuit board. In addition, power supply current is supplied to the electronic components via the power supply wiring, the via, and the power feeding terminal of the printed circuit board. In order to secure a power feeding amount, a plurality of power feeding terminals may be provided on the electronic component, and a plurality of vias and a plurality of power feeding terminals may be formed on the printed circuit board. In recent years, as the current supplied per one element has become larger, the number of pins of a power feeding terminal in the element is being increased. Accordingly, many power feeding terminals may also be disposed on the printed circuit board.
In addition, as a technology of controlling the distribution of current on the printed circuit board, a technology of limiting the direction in which current flows by forming a slit in a planar power supply wiring for supplying power from a power supply to an LSI circuit has been proposed. In addition, there has been proposed a technology of branching, on a board, a power supply wiring in isometric manner in the form of a tournament by taking any one point on the upstream side of a current path as a branch point, and connecting an electronic component to each of plural ends of the power supply wiring obtained by branching.
In the conventional printed circuit board having plural power feeding terminals, resistance components of current paths, which lead to the respective power feeding terminals, become uneven due to the difference in the positions at which the respective power feeding terminals are disposed, which causes the power feeding amounts from the respective power feeding terminals to become uneven. Thus, there is a possibility that excessive current may flow in a portion.
The followings are reference documents.
[Document 1] Japanese Laid-Open Patent Publication No. 2011-198827,
[Document 2] Japanese Laid-Open Patent Publication No. 03-036791,
[Document 3] Japanese Laid-Open Patent Publication No. 2005-012088,
[Document 4] International Publication Pamphlet No. WO 2012-039269, and
[Document 5] Japanese Laid-Open Patent Publication No. 2008-210944.